Cytologic and Surgical Correlation of TERT -Mutated Indeterminate Thyroid Nodules: A Case Series

Introduction Telomerase reverse transcriptase ( TERT ) promoter mutations is a relatively novel mutation that has been linked with thyroid cancers. This study examines the frequency, cytology and histo-morphologic features, and clinical outcomes of TERT -mutated indeterminate thyroid nodules. Methods A retrospective review of Bethesda III and IV thyroid cytology specimen sent for ThyroSeq ® testing (2019-2022) was performed, selecting those with TERT mutations. Demographics, cytologic features, surgical diagnoses, and follow-up data were analyzed. Results Among 567 specimens tested, 12 (2%) harbored TERT mutations; 4 had TERT alone, and 8 had additional mutations. Average age of patients was 69 years (92% > 50 years). Eight had surgical follow-up: 50% were malignant, 25% were benign and 25% were of uncertain malignant potential. Additionally, 62% were oncocytic nodules. Clinical follow-up showed all evaluated patients were alive without recurrences or metastases at last contact. Conclusion In our cohort, TERT promoter mutations were rare in indeterminate thyroid nodules (2%) and frequently accompanied by additional molecular changes. It is more frequently detected in older patients. Unlike prior reports describing TERT mutations exclusively in malignant thyroid tumors, our findings encompassed a broader histological spectrum, including benign, uncertain malignant potential and malignant lesions.